Determination of aluminium content in welding metal by thermoelectric means and its relationship with mechanical properties

Since aluminium is the third most abundant element in the Earth’s crust and has more and more applications at an industrial level, as well as its increasingly common presence in aluminised steels due to its excellent benefits such as anti-corrosion, antioxidant protection and good heat resistance, it is necessary to know its behaviour when present in welded joints. However, due to the possible presence of aluminium in the joint, defects appear which reduce the mechanical properties of the weld. In this research work the effect caused by the aluminium content in a welding metal and its variation in mechanical properties such as hardness and impact toughness is investigated through the use of a non-destructive thermoelectric technique. The sensitivity of the thermoelectric potential technique to detect microstructural and chemical composition changes was confirmed. The evolution of absolute thermoelectric potential (TEP) values with respect to the percentage of aluminium added to the weld was observed, being also quite sensitive to defects such as porosity and micro-cracks.